I take it as being for a supplement for multiple species of birds. I didn't see anything bad in the parts I could read. You could check the web site to see if it recommends anything for chickens. I couldn't quite read that. What form is it in powder, clumps or pellets? If it was a powder It might be hard to feed with scratch without mixing it with something to adhere it to the grain.

If its made for birds it should be okay. If it works or not, only time will tell.

Be sure to measure it properly if your mixing and don't over feed . I think it says a pinch?

The only thing I would be concerned about is the Iron. Be very careful with iron and do not over feed this particular supplement. I don't see that it says chelated. Chelated Iron is fine (will not build up if given in excess). Other forms however, can become poisonous to the bird.